Coated article.



P. MoILROY. COATED ARTICLE. APPLIUATION FILED 001216, ma.

`Patented May 12, i914,

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INVENTOR 6% it? I V WITN ESSES I cura @wm D sTArnsmPATENT OFFICE.

'PETER MCILROY, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB '.lO ENAMELED METALS COMPANY, 0F SHARPSBURG, PENN SYLYANIA, A CORPORATION OF PENNSYLVANIA.

COATED ARTICLE.

To all vellum' it in. f1.1/ concern Be-it known that l', Pn'run MCTLROY, a citizen of the -United States, and a resident ot' Pittsburgh, North Side, iu the county of Allegheny and State oit Pennsylvania, have invented a new and useful Improvement in Coated Articles; and l do hereby declare the following to be a full, clear, and exact description thereof.

My invention relates to coated articles and has special reference to the coating of metal articles, such as pipes, plates, ete.

In the manufacture of coated metal articles, such as what are known as galvanized pipes for electric conduit purposes, such conduits have been generally formed by a zinc coating electro-plated on the exterior of the pipe and an enamel` or other coating on the interior. These articles such as conduits are usually made of steel but may be made of east iron or any ferrous metal. In the manufacture of these zincplated pipes there are two methods generally employed, one known as the continuous process in which the pipe is electro-plated horizontally and the other in which the pipe is so treated perpendicularly. W'ith the first named method it is possible to deposit the zinc without first applying what is known as a strike coat, as the pipe can be brushed and cleaned and immediately plunged into the zinc bath'so that it does not have time to tarnish. With the other or second named method it is yimpractical to zinc -coat Without first using a strike. The pur ose of this strike is to deposit a coat o some metal which will adhere to the pipe more readily than zinc and up to the present time a copper strike has always been used and then the zinc coat-- ing is put on in the usual way in a separate tank. When no strike is used, it is a matter of chance whether the pipe will plate equally over its entire length, (as with this method, viz., perpendicularly, it lis not practical to immerse the pipe in the zine bath soon enough after being cleaned to prevent slight oxidation taking place, and no article will plate equally over its entire surface nnless the entire surface is equallyl clean). When the strike is used the current employed `in applying the strike acts as an electric cleaner, so that such pipeis cleaned equally throughout its entire length, and the strike coat is deposited uniformly all over the pipe. The current, acting as an' Specification of Letters Patent.

Application filed October 16, 1913.

Patented May 12, 19.14. serial No. 795,441.

electric cleaner, also forces out all acids and lmpurities that may be in the niinute pores of the metal, allows the strike coat to be deposited in these pores and removes danger of spotting out, 'which is liable to occur on any plated article not properly cleaned.

The object of the present invention is to provide for using a strike c at in place of such copper strike, by whichja better and more uniform coating1r of zinc is deposited on the pipe than with the use of either the copper fstrike or with the process in which no strlke is used, while the substituted strike for the copper strike is also much cheaper than the latter.`

To these ends my invention consists, generally stated, in the novel coated article, as hereinafter more specifically set forth and 'described and particularly pointed out in the claims.

To enable others skilled in the art to which my invention appertains to construct and use my improved coated article, I will describe the same more fully, referring to the accompanying drawing, in which F igurc 1 is a side elevation` partly broken away, of a pipe for electrical conduit purposes showing my invention applied thereto. Fig. 2 is a cross-section of the same.

Like symbols of reference herein indicate like parts in each of the figures of the drawing.

As illustrated in the drawing, 1 represents a pipe, which is formed of any suitable metal, such as steel, and such pipe is subjected to the followingr treatment for using the same as a conduit for electric wires. The pipe is first immersed in an alkali bath to clean the same by removingl all oils and grease therefrom, after which it is pickled in an acid bath to further clean the same by removing the scale therefrom, and then it is immersed in a'lime or other bath to neutralize the picklingr acid. The pipe is then brushed inside and outside in any suitable manner to remove any oxidation that may have taken place on the pipe after it Ahas been exposed to the air from the last named bath, and after which it is again immersed in an alkali cleaning bath to prepare it for the plating bath. The pipe is now readv to be electro-plated and this is accomplished in two operations or two coatings. Tn the first, a coat-ing 2 is deposited on the pipe in the usual electro-plating manner by immersing the'pipe in a bath, and such coat is` called a strlke coat, which consists of' a mixture of copper and zinc in certain proportions, as may be required, a preferred or goedl proportion being forty (40) per cent. ofcopper and sixty (60) per cent. of zinc, which practically makes a brass colored coating on the pipe. A coating 3 of zine is then applied on top of the combined copper and Zinc alloy coating on the pipe by the usual electro-plating process in another separate bath. It will thus be seen that in my improved coated pipe, the strike coat appliedthereto reduces all danger of what is known as spotting ont to a minimum and the pipe finished with .a much better color by being Whiter and more uni form. The percentage of the pipe failing to plate properly with the Zinc coating is greatly reduced, and practical experience has proventhat about ninety-nine (99) per cent. of the output Will plate perfectly, which is much higher than ythe first approved processes practised Without a strike 7 coat or With a copper strike coat. It has been practically proven that a pipe having a strike coat ofthe kind described, (before heilig plated With zinc, Will never deteriorate through galvanic action taking place,) and it has also been proven that a pipe having a strike .coat of either .copper or the alloy described will show less corrosion than zinc alone, so that a strike coat of any kind is preferable to none at all.

.Some of the advantagesof a pipe coated as above described are as follows: It minimizes the danger of acid being left in the pores of the metal of the pipe to destroy the zinc coating. (Pipe coated in this manner has a better appearance, being Whiter and more uniform 1n color.)

The manufacturing cost is reduced owing to there be ing less imperfect coatings, While the copper strike coat is more expensive, as copper is sold at a higher price than zinc. The pipe as thus coated resists corrosion much better than pipe plated Without a strike coat and it is possible to put a lighter coating of zinc on the pipe, if desired, than by the other known methods, and it also takes less time to put the described strike coat on than the copper strike l/Vith the zinc coating applied to' the strike coating described, a more tenacious coating of the Zinc will be had andaheavier coating of zinc can be applied Without danger of peel. lng.

Various modifications and changes in the process described and in the proportions used, as Well as in the application'of the same may be resorted to without departing 'from the spirit of the invention orl sacrificing` any of its advantages.

lVhat I claim as my invention and desire to secure by Letters Patent, is:-

l. A metal article having a strike coating of copper and Zinc applied to the saine and a coating of zinc applied to said first named coating.

2. A ferrous article having a strike coating of copper and zincapplied to the same and a coating of zinc applied to said first named coating.

3. A steel article having a strike coat-ing oicopper and zinc applied to the same and a coating of zinc applied to said first named coating.

In testimony whereof I, the said Pn'rnn MCLROY, have hereunto set my lia-nd.

PETER MCLROY.

W'it-nesses 2 S.A E. vHEDDEN, J. N. COOKE. 

